I recently read a book on Francis Schaeffer for class. Being a thorough look at Schaeffer, it inevitably spent time on Schaeffer's critique of Barth — indeed, it expanded the attack. It also applied Schaeffer's critique of culture to argue that Postmodernism is not a friend to Christianity.
Part of Schaeffer's issue with Barth was that he believed that Barth was agreeing to isolate faith from reason — that Barth accepted Kant's division between noumena and phenomena. However, I believe the fundamental misunderstanding on the part of Schaeffer and those like him is that they do not realize how far the postmodern critique goes, and therefore assume this is a discrediting of Christianity.
Rather, leaning heavily on Spirit-authentication and witness to the Word is acceptable, because it offers more certainty within a postmodern framework than we can provide to anything else. Postmodernism critiques not just religious knowledge, but also scientific knowledge. While Barth (and Calvin) both appeal to the primacy of what we might call a subjective authentication of God's Word, this is not relegating religion to some undesirable country, but rather showing it's uniquely authoritative status. Christianity has the singular status of being authenticated by the ever elusive center to which we otherwise are forced merely to circle around. Science, while remaining worthy, is not given such a handy escape and is left to continue to fend itself off from epistemological attacks.
To me, this seems like a satisifying answer to Schaeffer's critique, but I have only started to mull this answer over the last few days. What do you think?